This invention relates to developments of the technology described in patent publication number WO-95/35457 also U.S. Pat. No. 5,827,042.
The technology provides a combined seal and bearing assembly apparatus, comprising a stator and rotor adapted for rotation about an axis. The apparatus may be installed in place of the stuffing box of a centrifugal pump.
The rotor and the stator components are formed with complementary bearing-surfaces, which are so arranged as to sweep each other in a hydro-dynamic-bearing relationship, over an area termed the bearing area. One of the bearing-surfaces is formed with a groove, which extends in a spiral configuration along and around the bearing-surface, over the bearing area. The spiral-groove comprises several turns extending over the bearing-surface, the arrangement thereof being such as to leave lands of substantial width between adjacent turns of the spiral-groove. The spiral-groove has an entry-mouth and an exit-mouth.
The apparatus is so structured as to define an entry-chamber and an exit-chamber, being chambers which are in fluid-conveying-communication with the entry-mouth and the exit-mouth respectively, and the apparatus includes a means for conveying a barrier-liquid into the entry-chamber, and away from the exit-chamber. When the apparatus is driven in rotation, the barrier-liquid flows along the spiral-groove from the entry-mouth to the exit-mouth.
The apparatus is so structured that the fit of the bearing-surfaces is a tight running clearance, the clearance or gap between the surfaces being small enough, and the land width between the turns being wide enough, to ensure the establishment and continuance of a hydro-dynamic film between the bearing-surfaces. The bearing surfaces are conically tapered, and either the rotor or the stator is made axially movable into and out of the taper.